Eau Claire Formation Research Articles

The fate of trace elements during several coal pretreatment processes : Yan, R. et al. Energy & Fuels, 2002, 16, (5), 1160-1160

Recently, brine samples from the Cambrian-age Mount Simon Formation (the deepest, most inaccessible sedimentary rock formation of the Illinois Basin) and the overlying Ironton–Galesville Formation were collected as part of a major research effort evaluating the feasibility of sequestration of carbon dioxide in deep geologic formations. Halide and halide/cation ratios (especially Cl/Br and Na/Br ratios) from groundwater samples collected during this investigation suggest that the brines of the Cambrian-age strata formed by the evaporation of seawater well beyond the point of halite precipitation. The Cl/Br and Na/Br ratios, the presence of Mississippi-Valley-Type (MVT) ore mineralization in close proximity to the Illinois Basin, and the tectonic history of the region and the Illinois Basin suggest that components of ore-forming brines and perhaps crystalline basement brine are likely still present within the Mount Simon Formation. Halide and cation/halide ratio plots show that these brines have mixed with and have been diluted by subaerially evaporated seawater, seawater and dilute groundwater. Movement of brines out of the Mount Simon Formation and/or exchange with brines of other formations is constrained by the overlying, siltstone- and shale-rich Eau Claire Formation, a low-permeability layer.The most plausible interpretation of the halide and halide/cation ratio data is that the brines of the Cambrian-age strata were introduced to the Illinois Basin from outside of the basin, perhaps when the Illinois Basin was connected to the Arkoma (Oklahoma and Arkansas) and Black Warrior Basins (Alabama and Mississippi) via the Reelfoot Rift during Cambrian and early Ordovician time. In addition, the presence of some percentage of high NaCl, low Cl/Br brines from the crystalline basement is suggested given the geochemical relationships of the halide and cation/halide ratios and the tectonic history of the Illinois Basin. Finally, halide and cation/halide ratios determined by this investigation, and regional geochemical evidence and hydrogeologic modeling (by others) suggest that the brines of these strata probably were affected by regional hydrothermal activity during Permian time that was responsible for the MVT ore deposits of the Midwestern U.S. Thus, the brines of the deepest strata of the Illinois Basin constitute a different, more complex type of fluid than those found elsewhere in the basin. Halide and halide-cation ratios suggest that these deep brines are dominated by residual evaporitic brine (possibly originating as ore-forming brines) with dilution by seawater and dilute groundwater. Other components may include subaerially evaporated seawater and crystalline basement brines.

Circumocular suture and visual surface of“Cedaria” woosteri(Trilobita, Late Cambrian) from the Eau Claire Formation, Wisconsin

Rare specimens of the Late Cambrian primitive libristomate trilobite“Cedaria” woosterifrom the Eau Claire Formation of north-central Wisconsin preserve an unusual and new ocular suture, and the impressions of lens facets. The suture is circumocular, but loops abaxially onto the ocular platform. The portion of the ocular platform that is enclosed by this suture and is fused with the visual surface is here termed the “ocular plate”. The size and arrangement of the lens facets show that “C.”woosteripossessed a holochroal eye, typical of that known in other Cambrian libristomate trilobites. This nearshore assemblage, while low in diversity, contains a disparate array of trilobite morphotypes.

Biostratigraphic significance and paleogeographic implications of Cambrian fossils from a deep core, Warren County, Ohio

A deep core from Warren County, Ohio, has yielded numerous fossils of Cambrian age. The specimens, which are among the first recorded from Cambrian rocks of Ohio, suggest revisions in the inferred ages of the Eau Claire and Mount Simon Formations in the Cincinnati Arch region. Trilobites indicative of Dresbachian (late Middle Cambrian to early Late Cambrian) and possibly Franconian (Late Cambrian) age are present in the upper Eau Claire Formation. By implication, the underlying Mount Simon Formation must be of earlier Dresbachian age or perhaps older. Identified trilobites from the Eau Claire Formation seem to be characteristic of inner-shelf lithofacies of Laurentia. Other body fossils from the Eau Claire Formation include inarticulate brachiopods and a graptolite. Body fossils in the lower Knox Dolomite include trilobite sclerites and echinoderm ossicles. Trace fossils are present in both units.

Subsurface Stratigraphy and Structure of Sauk Sequence of Northern Ohio: ABSTRACT

The lower Paleozoic Sauk sequence of northern Ohio represents a carbonate and clastic sedimentary sequence deposited during the late Late End_Page 1440------------------------------ Cambrian Saint Croixan and early Early Ordovician Canadian. It is bounded below by the unconformity on the Precambrian basement and above by the Knox unconformity. The Sauk sequence was deposited throughout the study area of northern Ohio, which includes the western portion of the Appalachian basin, the Ohio-Indiana platform to the west, and the southernmost portion of the Michigan basin northwest of the Ohio-Indiana platform. The major lithostratigraphic units, all in the subsurface, are the Cambrian Mount Simon Sandstone, Shady Dolomite, Eau Clair Formation, Rome Formation, and Kerbel Formation, and the Cambrian-Ordovician Knox Group. Stratigraphic interpretations generally show that the Sauk sequence begins with clastic deposition occurring in the north-central and western portions of Ohio and predominantly carbonate and open-marine clastic deposition occurring in eastern and south-central Ohio. The location of the present Cincinnati arch marks a transition zone between the two sedimentary regimes. The final stage of Sauk sequence deposition was marked by a major marine transgression that resulted in deposition of the Knox Dolomite over the entire study area. Producing reservoirs occur in four stratigraphic-structural settings. The Copper Ridge Dolomite (Knox Group) on the eastern edge of the Ohio-Indiana platform has oil production from glauconitic sandstone reservoirs. Basinward, the Cambrian dolomitic Rose Run Sandstone Member occurs at the top of the Copper Ridge Dolomite. Mainly gas has been discovered in the Rose Run in secondary reservoirs formed during erosion of the Knox unconformity. Middle Ordovician shales and impermeable limestones are the seals. The majority of hydrocarbon production from the Knox Dolomite is located in central Ohio's Morrow County where erosional remnants of vuggy dolomite on the Knox unconformity form paleotopographic highs with Middle Ordovician shale as the seal. Other small pools consist of vuggy dolomite reservoirs with small structural closures. Although no significant amounts of hydrocarbons have been discovered below the Copper Ridge Dolomite, high porosities and permeabilities in the Mount Simon Sandstone and Eau Claire Formation lend potential to these rocks for liquid waste disposal. End_of_Article - Last_Page 1441------------

Sauk Sedimentation Patterns in Indiana and Adjacent States: ABSTRACT

The Sauk Sequence in Indiana and adjacent states is composed of two supergroups in mutual facies relationship, the Potsdam below and the Knox above. The Potsdam Supergroup contains, in ascending order, predominantly siliciclastic rocks that include the Mount Simon Sandstone, End_Page 1454------------------------------ Eau Claire Formation, Galesville Sandstone, Ironton Sandstone, and Franconia Formation. The Davis Formation replaces the latter three where they cannot be differentiated. The age of the Potsdam ranges from pre-Dresbachian through Franconian. The Knox Supergroup consists in ascending order of predominantly carbonate rocks of the Potosi Dolomite, Oneota Dolomite, Shakopee Dolomite, and Everton Dolomite. The age of the Knox rocks ranges from Franconian through Whiterockian. Cambrian sedimentation in pre-Dresbachian time is poorly known and may be restricted to fault-block basins. Terrigenous sand and mud were deposited in peritidal and shallow subtidal, predominantly marine, environments in the early Dresbachian. By the late Dresbachian, carbonate sand and mud, including oolite shoals, accumulated in the south, whereas marine terrigenous sand and mud were deposited in the north. In the Franconian, a bi-lobed delta complex, not yet well understood, dominated by terrigenous sand and mud, formed to the north, and the earlier shallow marine environment of carbonate deposition in the south expanded northward, so that by the end of the Franconian, pervasive carbonate deposition was extremely widespread. The Oneota and Shakopee rocks were deposited in widespread shallow marine environments, and the record of marine sedimentation of Everton rocks is restricted to the southwestern part of the study area. Extensive post-Knox erosion has greatly reduced the original distribution of the Sauk Sequence, and rocks of the Chazyan are unconformably juxtaposed with rocks as old as Franconian. The distribution of rocks at the top of the Sauk and the consideration of the internal stratigraphy of the Sauk should influence future decisions for petroleum exploration, underground gas storage, and deep-injection liquid-waste disposal. End_of_Article - Last_Page 1455------------

Early Paleozoic Sedimentation in Reelfoot Rift: ABSTRACT

Analysis of subsurface data from deep tests drilled in the northern Mississippi embayment and southern Mid-Continent suggests that earliest Paleozoic sedimentation was dominated by the tectonic evolution of the Reelfoot rift. Throughout most of the Mid-Continent, the Upper Cambrian Lamotte (Mt. Simon) Sandstone rests nonconformably on Precambrian basement and is overlain by the Bonneterre (Eau Claire) Formation. However, in the area of the Reelfoot rift, both the Lamotte and Bonneterre grade into thick, basinal shales that locally display evidence of episodic deposition of coarse clastics, perhaps on submarine fans. Moreover, two major sedimentary units are present beneath the Lamotte-Bonneterre basinal facies within the Reelfoot rift. Immediately underlying the Lamotte-Bonneterre shale is a carbonate stratum (probably dolomite) that thickens to more than 1,000 ft (300 m) along the axis of the basin in eastern Arkansas. Underlying this carbonate is a detrital unit that grades from arkosic sandstone near the northern terminus of the basin to a basinal shale southward. This basinal shale is at least several hundred feet thick near the axis of the basin. These two strata occupy the stratigraphic position of the Conasauga (Middle Cambrian) and Rome (Lower Cambrian) Formations of the southern Appalachians. The axial and transverse distribution of these strata suggests that the Reelfoot evolved as paired grabens or half grabens during the Early and Middle Cambrian. Subsequently, the Reelfoot remained the axis for more widespread subsidence and sedimentation throughout much of the Paleozoic. End_of_Article - Last_Page 1456------------

Tidal Deposition in the Basal Upper Cambrian Mt. Simon Formation in Wisconsin

The Upper Cambrian Mt. Simon Formation (0-65 m thick) is a basal quartz arenite exposed in westcentral Wisconsin. A detailed field investigation of the physical and biogenic sedimentary structures of the Mt. Simon has led to the recognition of three distinct lithofacies. The lower one unconformably overlies Precambrian basement rocks. It consists of medium- to very large-scale sets of tabular and trough cross-bedded, medium- to very coarse-grained sandstone and pebbly sandstone with minor intercalated horizontal beds of very fine- to medium-grained sandstone, siltstone, and shale. Sparse examples of Skolithos and Arenicolites are present. This facies consists of a very thin sequence of possible braided-fluvial and marine foreshore deposits, overlain by probable marine shoreface and tidal channel deposits. Much of the facies seems to represent shallow subtidal deposition in a relatively high-energy regime. The middle lithofacies consists of two distinctly different subfacies, which probably were deposited in a low tidal flat setting. The higher-energy subfacies consists of small- to medium-scale sets of tabular and trough crossbedded, fine- to coarse-grained sandstones containing distinct zones dominated by Skolithos and Arenicolites . This subfacies probably represents deposition in meandering tidal channels. The lower-energy subfacies consists of thinbedded, horizontally-laminated and ripple cross-laminated, very fine- to medium-grained sandstone, siltstone, and shale, with common specimens of Cruziana, Rusophycus, and Planolites . This subfacies probably represents deposition on lower-energy tidal flats adjacent to the tidal channels. The upper lithofacies consists predominantly of structureless, densely bioturbated, very fine- to coarse-grained sandstone containing abundant specimens of Skolithos . The upper few meters of the facies consists of small- to medium-scale sets of trough cross-bedded, very fine- to coarse-grained sandstone with layers of disarticulated valves of the brachiopod Obolus . The upper facies probably represents deposition on tidal flats, perhaps in a midtidal flat setting, characterized by slower sedimentation rates, a correspondingly higher degree of bioturbation, persistent reworking of shelled macrobenthos, and periodic subaerial exposure. The Mt. Simon Formation is interpreted as a largely progradational (regressive), shoaling- and fining-upward tidal sequence. A marine interpretation is supported by the widespread occurrence of marine trace fossils within this unit. Evidence for a tidal origin is seen in the presence of unimodal cross-strata associated with reactivation surfaces, compound cross-strata, numerous scour and truncation surfaces lined with intraformational conglomerates, common clay drape laminae separating sets of cross-strata, interference and flat-topped ripple marks, and desiccation cracks. Sedimentation continued without apparent interruption as the overlying Eau Claire Formation was deposited. also under tidal influence. Recent reinterpretations of other basal Cambrian cratonic quartz arenites, together with this new interpretation for the Mt. Simon Formation, suggest that the long-held concept of basal transgressive sandstones deposited as blankets across the craton may be too simplistic, for deposition in braided-fluvial, marginal marine (tidal flat-tidal channel), and marine foreshore and shoreface environments seems indicated.

Cambrian Lithostratigraphy of Michigan Basin

The composite Cambrian sequence of the Lower Peninsula of Michigan consists, in ascending order, of the Mt. Simon Sandstone; Munising Group, composed of the Eau Claire Formation, Galesville Sandstone, and Franconia Formation; St. Lawrence Formation; Lodi Formation (a minor unit); and the Jordan Sandstone. They compose an estimated 3,000 ft (915 m) of section at the approximate depocenter, near or possibly in Ogemaw County. These rocks long have been an enigma to Michigan geologists because of a lack of both drilling information and outcrops. When viewed against the broad, regional stratigraphic framework and defined rigorously in terms of lithology, they are clearly identifiable as representing sedimentary facies deposited in or near the margins of a transgressive-regressive sea. The Mt. Simon Sandstone represents the high-energy shoreline facies of the northerly transgressing Cambrian sea. The glauconitic Eau Claire and Franconia Formations of the Munising Group are composed of sandstone, siltstone, and minor dolomite and shale interbeds which reflect a lower energy, near-shore marine environment. These two units can be distinguished from one another only where separated by the Galesville Sandstone, a regressive unit restricted to southern and western Michigan. Outside the depositional limits of the Galesville, there is present within the Munising Formation interbedded sandstone, dolomite, shale, and nodular anhydrite which, taken together, strongly suggest a shallow to supratidal environment of deposition. Known only in central Michigan, the areal extent of his facies is undetermined. Essentially a dolomite unit, the St. Lawrence Formation contains many chert and cherty sandstone interbeds in southwestern and western Michigan. The term St. Lawrence includes those stratigraphic elements called Trempealeau and Prairie du Chien in previous investigations. The St. Lawrence grades upward into the Jordan Sandstone, a regressive sandstone unit that documents the gradual infilling of the Michigan basin area. The Jordan Sandstone has been identified erroneously in prior reports as the St. Peter Sandstone of the Mid-Continent region, but the St. Peter was not recognized anywhere within the area of study. The top of the section is bounded by an erosional unconformity of regional extent on which rocks of the Glenwood Formation (Middle Ordovician) were deposited. The Mt. Simon through Jordan rocks form an essentially continuous sequence of deposition beginning with marine transgression probably in the Late Cambrian and ending with regression and regional uplift in the Early Ordovician. The sedimentary record clearly places the formation of the Michigan basin back at least to Late Cambrian time. In the light of the growing energy crisis in the United States, the clarification of the stratigraphic relations of these rocks should lead to increased interest in their petroleum potential.

Deep Well Disposal

AbstractDetails concerning the drilling and successful completion of a deep waste disposal well at Newport, Indiana are described. The well is 6160 feet deep and penetrates about 900 feet into the Mt. Simon Sandstone which is the reservoir for disposal of inorganic waste. Under natural conditions, the Mt. Simon is saturated with essentially stagnant brine. The Eau Claire Formation overlying the Mt. Simon has a near zero permeability, thus, preventing upward migration of waste. To date, millions of gallons of waste effluent have been pumped into the well at an average injection rate of approximately 70 gallons per minute.

Developments in Indiana in 1957

Oil production in Indiana during 1957 totaled 11,810,000 bbls., an increase of 33,000 bbls. over 1956 production, and 727 wells were drilled for oil and gas, as compared with 699 in 1956, an increase of 4.0%. Six new pools, 9 extensions, and 4 new pays in productive areas were discovered in 1957. Most of the drilling occurred in the southwestern part of the state, and most of the successful exploratory wells were completed in Mississippian formations. Five successful exploratory wells were completed in Pennsylvanian sandstones and 14 in Mississippian sandstones and carbonate rocks. More wells were drilled to older formations in Indiana during 1957 than in 1956. Two wells in northeastern Indiana penetrated the Eau Claire formation of Cambrian age, and five other wells were drilled to the Knox dolomite of Cambrian and Ordovician age.